Matt Jones/Redbook(NEW YORK) -- Kim Kardashian and her boyfriend of more than a year, Kanye West, are expecting their first baby this summer — but according to the starlet’s sister, their romance was slow-moving.

“He always had a crush on Kim but she was never into him at the time,” Khloé Kardashian tells Redbook magazine. “Then one day she says, ‘I think I like Kanye.’ I was like, ‘Since when?’”

Kardashian, 28, tells the magazine in its June issue that she and her family have known the rapper since 2004, and she’d always encouraged the romance.

“I always told Kim they were like two peas in a pod,” she says. “She would never listen!”

But the Keeping Up With the Kardashians star also admits to the magazine that her outspoken nature (she has openly discussed her trouble conceiving a baby) has led to some frustration too.

“Do I wish people would quit asking me about it 24/7? Yes, but I don’t regret it,” she says. “I was 26 when that started and I admit, I didn’t know a lot about my body. It was hard for me to understand what was happening because my mom had six kids and [older sister] Kourtney got pregnant quickly.”

Still, Khloé Kardashian, who married NBA player Lamar Odom in 2009, says that she’d taken shots to stabilize her hormones, but because of her schedule, it was difficult to be consistent — a sign, she says, that “the timing was just off.”

“People assume I’m desperate for a baby. And yes, I would love to have a baby,” she continues. “I love my life, but it doesn’t feel incomplete right now.”